The long term objective of Phase II is to develop a reliable, safe, and rapid way of measuring body volume of humans and animals using acoustic plethysmography. Such a method will enable clinicians and researchers to evaluate the nutritional benefits of various feeding regimens and to determine the relative growth of body components. For Phase I, we propose to extend our work from successful operation of an acoustic plethysmograph used to measure small volumes in an anechoic chamber to measure larger volumes in a non-anechoic chamber environment and at the same time to extend our understanding of the effects of various parameters on the accuracy of the acoustic plethysmograph. In Phase II, we will test the accuracy of the scaled-up versions of the acoustic plethysmograph using humans and animals such as swine and calves and automate the operation of the plethysmograph in order to minimize operator error when taking measurements. Commercial opportunities will come from organizations studying humans and animals such as: 1) Clinics and research units studying nutrition and body development, 2) agricultural companies studying animal nutrition to improve the breeding and feeding of animals, and 3) sports organizations, professional, college and high school, interested in the body composition of athletes.